Actually, some of the people this address was given to would go on to create the SPD and Marx and Engels would support them. The SPD, though it contained a conservative wing, would remain the party of the German proletariat until it split over supporting the first World War and the Bolsheviks in Russia.
I’m not sure what specific names the German petty bourgeois were organizing under in 1850 but at the end of the Communist Manifesto they discuss a number of trends in German politics that would include the petty bourgeoisie.
Very much social democratic with a revolutionary veneer. They run Organizing for Power which promulgates the organizing model of “don’t do anything unless 90% of the workforce basically already agrees with you”.